"Some might be turning away from meth and moving more toward heroin," said Dan Banasik, a Missouri State Highway patrol trooper assigned to the Drug Enforcement Administration's Springfield office.

Others, Banasik said, who get hooked on prescription painkillers might move to heroin to feed their addiction.

"And, of course, who has the heroin?" Banasik asked rhetorically.

Like meth, Mexican drug cartels have been smuggling heroin into the Midwest in ever-increasing quantities, he said.

Even rural areas are experiencing growth in heroin distribution. The Missouri Legislature has taken note. In May, legislators passed a bill that would let trained responders use naloxone to treat people who overdose on heroin or prescription painkillers. The bill is awaiting final action by the governor.

George Larby, who heads the Combined Ozarks Multijurisdictional Enforcement Team, known as COMET, said the recent spike was surprising.

"I've been in long enough to remember when heroin was in Springfield. It was here and there a little but then it was gone. Now, all of a sudden, it's popping up again."